Fuel pump



Nov. 20, 1934. E. A. RocKwELL FUEL PUMP 2 Sheets-Sheet l Filed NOV. 26, 1928r j'f @si 2 Sheets-Sheet -2 Nov. 20, 1934. E. A, RocKwELl.

FUEL PUMP Filed Nov. 26, 1928 Q v m d Patented Nov. 20, 1934 UNITED STATES 'PATENT oFFlcE 7 Claims.

The purpose of this invention is to provide an improved construction for supplying fuel to the carbureter of an internal combustion engine by means adapted to ensure at all times an adequate supply and avoid excess supply or excess pressure of the supply upon the carbureter. It consists in the elements and features of construction shown and described as indicated in the claims. In the drawings:

Figure 1 is a `diagrammatic view for showing the location of the parts constituting the invention with respect to the carbureter and the fuel source.

Figure 2 is a side elevation of the structure embodying the invention shown detached from the engine and from the fuel source.

Figure 3 is a top plan View of the same.

Figure 4 is a section at the line 4-4 on Figure 3.

Figure 5 is a detail portion of Figure 4 upon an enlarged scale for showing the valve construction.

In the drawings the engine carbureter is indicated at A, thel fuel source at B, and the pumping device constituting the invention is indicated in totality by C.

The pumping device formed for mounting on the engine body comprises a casing member D, which contains a cylindrical fuel chamber, 10, one end of which is closed by a flexible diaphragm, 1l, the opposite end being bounded by a shell member, l2, comprising a hollow cylindrical p0rtion, 13, which is intruded into said opposite end of the chamber, 10. Said chamber, l0, has connections, indicated at 14, for deriving'fuel supply from the fuel source, B, and the shell member, 12, has connection, indicated at 15, for delivery of fuel to the carbureter A. The exible diaphragm, 11, which closes the upper end vof th'e cylindrical chamber, l0, is clamped in place for closing said chamber by means of a casing cap member, D1, said cap member and the chamber member, 10, having annular anges, d, d1, mated for clamping between them the annular margin of the diaphragm, l1, as may be clearly understood from Figure 4. A plunger of which the head, 16, consists of a hollow cylindrical shell adapted to telescope pistonwise outside the intruded shell member, 13, is operated by a two-membered stem, of which one member, 17, is secured to the center of the flexible diaphragm, 1l, having the portion, 17a, extending above the diaphragm and obtaining slide bearing at 18 in the cap member, D said stem being reduced, as seen at 19, forming a shoulder, 20, for clamping the diaphragm at its central area, which is effected by means of said shoulder, 20, at the upper side of the diaphragm, and a nut, 21, engaging the thread on the reduced part of the stem and clamping against the lower side of the diaphragm a washer, 22, which serves a `further purpose hereinafter described.

The second stem member consists of an integral cylindrical stem extension, 24, of the hollow plunger head, 16, said stem member 24 having at its upper end an inwardly turned flange, 25, for engaging a stop collar, 26, which is secured at the lower reduced end of the stem member, 17, said stop collar being diametered for sliding it in theV cylindrical stem member, 24, the latter being cut away at the opposite sides at parallel planes, as seenV at 24a, for a substantial portion 70 of the length of said cylindrical stem, to effect free liquid communication from the chamber, 10, through said stem to the cavity of the shell plunger head, 16. A coil spring, 27, extends under compression between theplunger head, 16, and the flexible diaphragm, 11, at which latter the washer, 22, serves for centering and stopping the end of the spring, said washer being peripherally anged to form a hood over the upper end of the spring. The spring is centered at its lower end by proximate fit outside the cylindrical stem, 24. In said cylindrical stem at the lower end there is located a disk valve, 28, which seats upwardly upon a valve seat member, 29, tted within the lower end of said cylindrical stem member, that is, above the junction of said stem member with the hollow plunger head, .16, with which said stem member is integral as mentioned; and a coil spring, 30, is provided reacting upon the disk valve for holding it normally seated upwardly on said valve seat, the spring being stopped at its lower end by a spider, 31, which is secured to the lower end ofthe seat member, 29, the Valve, 28, and spring, 30, being assembled in the valve seat member, 29, and secured in place by the spider, 31, clinched to the lower end of the valve seat member, and thus constituting a valve unit which is secured in the lower end of the stern member below the lateral cut-away part, said valve seat member being dimensioned for drive fit at this position in the tubular stem member, 24. In the upper end of the intruded cylindrical-shell member, 13, there is mounted a second valve unit comprising a seating member, 33, for a disk valve, 32, held seated by a spring, 34, retained by a spider, 35, at the lower end of the valve seat member, the entire unit construction being identical with that of the unit comprising the valve, 28, and being dimensioned as to the valve seat member for drive t within a downwardly protruding 11o ange, 37, extending from the inner circumfenential margin of anaperture in the head of the shell member, 13, the diameter of' said valve being that of the tubular stem member, 24, so thatthe two valve units are in all dimensions equal in their several parts. Y

The order of assemblage of the construction as thus far described may be understood to be as follows: The stem member, 17, is secured to the diaphragm, 11, being inserted through the diaphragm from the upper side, the washer, 22, be-l ing introduced over the reduced lower end ofthe stem followed by the nut, 21, which is tightened for clamping the washer and thereby the dia' phragm against the` shoulder,l 20. v The stop collar, 26, and nut, 26u, are introduced through the plunger head, 16, into the tubular stem, 24; the coil spring, 27, is next introduced outside the tubular stem, 24, and the stem member, 17, now carrying the diaphragm is introduced downwardly through the coil spring, 27, vand through the collar, 26, and the nut, 26a, manipulated by a suitable tool through the coilsofa `coil spring, 27, is screwed onto the threaded end of the stem, 17,'clamping the collar, 26, securely on said stem, the coil spring, 27, being in this process compressed to.the proper degree for functioning asvk hereinafter described.v .Y

Or when the stem member, 17, has been secured, as described, to theA diaphragm, the coil spring, 27, being compressed to the-limit and temporarily tied in such compressed condition, in which its length will be less than that of the tubular stem, 24, will be'introduced outsidel the stem, 24, and the stem member, 17, being inserted through the stem, 24, and the coil spring, 27, the stop'collar, 26, in the nu-t, 26H, may be applied to the end of the stem which will be accessible for that purpose through the plunger head, .16. The

coil spring being then untied and released, will retract the collar, 26, into the tubular stem to the stop fiange, 25,at the upper end of said tubular stem.

'I'he valve unit comprising the valve, 28, is now forced into the lower end of the tubular stem, 24; and the assemblage from the diaphragm to the plunger head, 16, is ready for mounting .in the casing member, D, and for clamping the diaphragm between the mated annular marginal flanges, d, d1, of the casing members, D and Dl. The cap member, D1, has a horizontal lateral hollow arm, D2, terminating for protruding into the engine casing, as seen at d2, and having a flange, d20, for stopping and securing the entire pumping device on the engine body. vAt a pivot, 41, in the terminal, d2, which protrudes intothe engine casing, there is fulcrumed a lever, 50, having a terminal, 52, at the inner end for cooperating with the cam, 53, on a shaft, 54, of the engine, the opposite arm of the lever extending through the casing cap arm, D2, has a terminal, 54, which protrudes into a slot, 55, in the upper end portion of the stem, 17, below the slide bearing, 18, for engaging the stem, 17, in the positive stroke of the lever, 50, produced by the cam, 53, the stem, 17, being provided with a plug, 58, of non-resonant material for encounter of the lever terminal, 43, in the positive stroke and avoiding undesirable noise in such encounter.

At the upper end the stem, 17, protruding from the upper end of the bearing provided for it in the cap member,'D1, is encompassed by a coil spring, 61, for which a seat is provided at the lower end in the upper end of the slide bearing upper end of the stem having its head overhanging the upper end of the spring, serves as a stop for that end; whereby the reaction of the spring between the casing cap member, D1, and the stem, operates for upholding the stem and the plunger head for retracting the same, thereby operating to hold the lever-encountering plug, 58,v against the lever terminal, 43throughout the entire cycle of action-of the cam including its positive action upon the lever and the withdrawal of its eccentric protrusion therefrom, thus tending to keep the lever at all times in contact with the cam, avoiding any annoying or injurious knocking of the parts in operation.

The operation of this structure for supplying fuel to the engine may be under-stood from the foregoing description to be as follows:

Assuming the parts at the position shown in Figure 4, the chamber, 10, bzing connected for fuel inflow from the fuel source, and the cylinder head member, 12, being connected for supplying fuel to the carbureter, upon the rotation of the engine shaft carrying the cam, 53, from the startinglposition indicated, which is the position of maximum actuation of the lever, 50, by the cam, the plunger stem, 17, is retracted by the reaction of the spring, 61, and retracts the plunger head, 16,` by the engagement of the collar, 26, with the inturned flange, 25, at the upper end of the tubular stem member, 24, of the plunger. This retracting movement operating the plunger head, 16, pistonwise with lrespect to the intruded shell member, l13, of the cylinder head, causing partial vacuum between the two pistonwise co-operating elements, and thereby also in thek chamber, 10, with the result eventually of causing fuel to be lifted by suction from the low 'level source and drawn into the chamber, 10,

which, eventually in the successive repetitions of the actions may become filled with fuel at least to the level of the fuel inflow connection indicated at 14.

In this suction stroke of the plunger produced by the reaction of the spring, 61, it will be observed that the coil spring, 27, is held compressed and thereby conditioned for reacting to the extent that it is released from the stress in the opposite direction of the spring, 61, by the positive action of the cam on the lever, 50, and through said lever on the stem member, 16, on the spring, 61, for thrusting the plunger in the direction for forcing the fuel which has been drawn into the pumping chamber out past the valve, 32, for iiow toward the carbureter, and it will be observed that the force with which this feeding action is performed can in no event exceed the reaction of the spring, 27, because that spring intervenes between the positively actuated stem member, 17, and the plunger, and there is a range of vertical play or lost motion between the two stemv members, 17 and 24, from the position at which the collar, 26, is stopped against the inturned ange, 25,

of the stem member, 24, and the valve seat mem.

It may be understood that the purpose of the construction, being, as described, such that the positive action of the cam can in no event cause any more positive feeding of the fuel than will be effected by the reaction of the spring, 27, is to fuel thereto with undue pressure. It will be recognized, furthermore, that while the positive action of the cam ensures adequate supply o f vfuel to be taken by suction from the low fuel source, this result is obtained not directly by positivev fuel lifting action of the cam, but by the reaction of the spring, 61, in which the force necessary for such lifting action is stored-by the action of the cam compressing this spring in the positive phase of the rotation of the cam.

At the lower end of the stem member, 1'7 there is provided a terminal element which preefrably is made yielding, as by being in the form shown consisting in a coil, 72, which encounters the check valve, 28, for opening it upon predetermined relative telescoping movement of the stem members, 17 and 24. This construction operates to cause, a limited opening of the fuel inlet valve, 28, toward the limit of the positively caused movement of the diaphragm in which the spring, 27, is compressed for reaction to give the full discharge stroke to the part, 16. This adapts the structure to afford a more uniform discharge pressure because it permits the employment of a stronger discharge spring, 2'1,k than would otherwise be suitable, and the discharge pressure can be maintained for full flow condition which will be re.- lieved for lesser flow, or at least for minimum flow conditions, by the slight opening of the inlet valve, as mentioned.

I claim:

1. A fuel feeding apparatus for an internal combustion engine comprising in combination witha casing having a fuel chamber provided with closures at both ends and connected for fuel inflow and outflow, the closure at one end comprising an inwardly protruded shell of less outer diameter than the inner diameter of the chamber, a plunger having a stem and mounted in the casing at the opposite end of the chamber having a head reciprocating in the chamber, and means for reciprocating it, said plunger head being a cylindrical shell open at the end and dimensioned for telescoping outside the first mentioned shell, whereby there is formed between said telescoping parts a pumping chamber, said parts having a fuel flow passage between the fuel chamber and said pumping chamber, a check valve controlling flow through said passage opening for flow outward from the fuel chamber, the first mentioned shell having a flow passage from the pumping chamber to the interior cavity of said shell, a check valve between the shell and the pumping chamber controlling said passage opening for flow outward from the pumping chamber, said interior cavity of said shell having connection for fuel flow toward the carbureter, said check valves being arranged to be actuated for opening and closing by the movement of the liquid pumped opening for flow outward from the pumping chamber and being seated by the reverse flow, the closure of the fuel chamber at the end opposite the intruded shell being a flexible diaphragm, the plunger stem comprising a member extended through the diaphragm for exterior actuation and secured fluid-tight to the diaphragm for flexing the latter in the reciprocation of the plunger, an operating connection outside the diaphragm for actuating the plunger in one direction, a spring reacting between the casing and the plunger stem member for retracting the plunger in the opposite direction, the plunger stem comprising a second member joined to the plunger head and longitudinally movable relaflxedly secured thereto tively to the first stem member, and a in the fuel chamber reacting between the two stem members for extending them, said steml members having cooperating stops for limiting such extension.

2. A fuel feeding apparatus for an internal combustion engine comprising in combination with a casing having a fuel chamber provided 'with closures at both ends and connected for fuel inflow and outflow, the closure at one end comprising an inwardly protruded shell of less outer diameter than the inner diameter ofthe chamber, a plunger having a stem fixedly secured thereto and mounted in the casing at the opposite nd of the chamber having a head reciprocating in the chamber, and means for reciprocating it, said plunger head being a cylindrical shell open at the end and dimensioned for telescoping outside the rst mentioned shell, whereby there is formed between said telescoping parts a pumping chamber, said partsv having fuel flow passage between the fuel chamber and said pumping chamber, a check valve controlling flow through said passage opening for fiow outward from the fuel chamber, the first mentioned shell having a flow passage from the pumping chamber to the interior cavity of said shell, a check valve between the shell and the pumping chamber controlling said passage opening for flow outward from they pumping chamber, said interior cavity of said shell having connection for fuel flow toward the carbureter, said check valves being arranged toA be actuated for opening and closing by the movement of the liquid pumped opening for flow outward from the pumping chamber and being seated by the reverse flow, the plunger stem consisting of two longitudinally aligned members adapted for longitudinal movement relatively to each other for extending the stem, stops von said members limiting such extension, and i a spring reacting between them for holding them normally extended to the limit determined by the stops, the means for actuating the plunger being ber within the fuel receiving chamber comprising a xed member and a member reciprocating for alternately enlarging and reducing the pumping chamber, said reciprocating member having a fuel inflow passage, a check valve therein operating for flow in one direction through the pumping chamber and seating against flow in the other directiornan operating stem for the reciprocating member having lost motion connection with said member, said stem having an extension projecting in the direction of the lost motion and dimensioned for encountering .thevalve of said reciprocating member in the chamber reducing stroke in the direction for opening the valve against pressure normally due to said chamber-A reducing stroke.

4. A mechanically'driven fuel pump comprising a pump casing having a chamber therein, a reciproca-ble pumping member dividing said chamber into a pumping chamber and a fuel receiving chamber, a valve controlled outflow passage from the pumping chamber, an inflow passage to said fuel receiving chamber, a flexible diaphragm secured in sealing relation to said casing and forming a wall of said fuel receiving chamber,-an operating member secured in sealing relation to said diaphragm and extending 5 therethrough, a lost motion connection within said fuel receiving chamber between said operating member and said pumping member, a resilient compression spring mounted 'between t said pumping member and said `diaphragm and serving to limit the effective discharge stroke of said pumping member, means 4for positively moving said operating member in one direction and resilient means operative to return said operating member in the opposite direction.

5. InA a fuel pump, a pump casing having a pumping chamber therein, a reciprocable pumping member forming a movable wall of said pumping chamber, an inlet check valve controlling an inflow passage leading to said pumping chamber, an outlet check valve controlling an outflow passage leading from said pumping chamber, a compression spring reacting upon said pumping member for lproducing the discharge stroke thereof, an operating member Ihaving a constant stroke for producing the suction strokes of said pumping member in one direction of movement and means for opening said inlet valve at the limit of movement of said operating member in the opposite ydirection when the pumping member has Ibeen prevented from moving for discharge from the limit of its suction stroke by the force of the discharge pressure.

6. A fuel pumping device comprising a fuel receiving chamber having fuel inflow connection with a fuel source, cooperating respectively fixed land reciprocable members constituting a pumping chamber located in the fuel receiving cham-y ber, the fixed member constituting a closure for one end of the fuel receiving chamber, operating means for the reciprocable member extending out through the other end of the fuel receiving chamber and comprising two stem members having 10st'l motion connection with each other within the fuel receiving chamber, a spring reacting between said stem members for normally taking up the lost motion and a flexible diaphragm constituting a closure for said other end of said fuel receiving chamber, one of said stem members extending through said diaphragm and made fast thereto, the end of the stem member extended therethrough being adapted to have energy applied to said end to flex the diaphragm in the movement for actuating the reciprocable member.

7` A fuel pumping device comprising a fuel receiving chamber having fuel inflow connection with a fuel source, cooperating respectively fixed and reciprocable members constituting a pumping chamber located in the fuel receiving chamber, the fixed member constituting a closure for one end of the fuel receiving chamber, operating means for the reciprocable member extending out through the other end of the fuel receiving chamber and a flexible diaphragm constituting a closure for said other end, said operating means comprising two stem members having lost motion connection with each other within the fuel receiving chamber, one of said stein members being joined to said reciprocable member for full movement therewith, the other of said stem members extending through said diaphragm and made fast theretofor flexing of the diaphragm in the movement for actuating the reciprocable v member, said reciprocable member having mounted therein a check valve which is normally closed against flow from the pumping chamber toward the fuel receiving chamber, said second mentioned stem member having an extension projecting towards said valve and ldimensioned for encounter therewith in valve-operating direction in the lost motion movement of said stem member.

EDWARD A. ROCKWELL. 

